JPH03231124A - Apparatus for measuring diameter of light beam - Google Patents

Abstract

PURPOSE:To measure the shapes and the diameters of light beams in the two directions on the same cross section at the same time by providing two slits which are not in parallel to each other on one plane that is orthogonal to the light axes of the light beams, moving the slits, and detecting the amount of transmitted light. CONSTITUTION:Slits 2a and 2b are provided so that the slits are intersected as a right angle. The amount of a light beam 1 to be measured which has passed through each slit is detected with a photodetector 3 and inputted into an amplifier circuit 6. A device 4 linearly moves the slits 2a and 2b so that each slit forms 45 deg. with respect to the longitudinal direction. A position detector 5 obtains the relative positions of the slits 2a and 2b. In this way, the light beam 1 is made to scan in the two orthogonally intersecting directions at the same cross section. Since the amount of each light beams passing through the slits 2a and 2b is sequentially changed, the shapes and the diameters of the light beam in the X and Y directions can be measured.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a measuring device for measuring the diameter of a light beam in a device that generates a light beam.

2. Description of the Related Art Hereinafter, a conventional measuring device for measuring the diameter of a light beam using a conventional slit will be described with reference to the drawings.

In FIG. 4, 1 is a light beam such as a laser beam, and 2 is a slit, which is movable in the X-axis direction. 3 is a photodetector.

The operation of the conventional example configured as described above will be described below.

A light beam 1 such as a laser beam is incident on a plane in which a slit 2, which is movable in the direction X perpendicular to the optical axis, is provided at a beam diameter measurement position. As the slit 2 moves, the amount of light detected by the photodetector 3 changes. The light, the shape of the beam, and the beam diameter can be measured from the signal of the amount of light and the amount of movement of the slit 2.

Problems to be Solved by the Invention However, with the above configuration, the diameter of the light beam can only be measured in one direction at a time on the same cross section, so in order to measure the diameter of the light beam in a different direction, the slit must be The problem is that it is mechanically difficult to measure beam diameters in two directions on the same plane almost simultaneously.

In view of the above-mentioned problems, the present invention provides a light beam diameter measuring device that can simultaneously measure light beam diameters in two directions on the same cross section.

Means for Solving the Problems In order to solve the above problems, the light beam diameter measuring device of the present invention has two slits that are not parallel to each other in the same plane perpendicular to the optical axis of the light beam, and a light beam that connects these two slits. It has a moving device that moves the beam in a direction perpendicular to the optical axis of the beam, and a photodetector that detects the amount of transmitted light of the light beam that passes through the slit.

Operation With the above configuration, the present invention can scan the slit in two directions with respect to the light beam by linear movement in one direction, so that the shape and diameter of the light beam in two directions can be measured simultaneously on the same cross section.

Embodiment A light beam diameter measuring device according to an embodiment of the present invention will be described below with reference to the drawings. In Figure 1,
1 is a light beam to be measured, 2a is a slit for measuring the beam shape and diameter in the X direction, and 2b is a slit for measuring the beam shape and diameter in the Y direction.These slits 2a and 2b are provided to be orthogonal to each other. . 3 is a photodetector with a slit 2a.

The amount of light beam transmitted through 2b is detected and converted into an electrical signal. Thereafter, the optical signal from the detector 3 is amplified by an amplifier circuit 6 to obtain a signal corresponding to the shape of the optical beam. Also, 4 is the slit 2a.

This is a moving device for linearly moving 2b in a direction making 45° with respect to each longitudinal direction, and for example, a stepping motor, a ceramic vibrator, etc. can be used. Then, the light beam diameter is determined from the relative position of the slit obtained by the position detector 5.

Regarding the light beam diameter measuring device configured as above,
The principle of operation will be explained below using FIGS. 2a-i.

By linearly moving the slits 2a and 2b in a direction making a 45° angle with the respective longitudinal directions, the light beam 1 to be measured is
The relationship between the slits 2a and 2b changes from a to i in the figure. First, in figure a, the light beam 1 to be measured is not transmitted at all. In b, c, and de, the amount of transmitted light of the light beam 1 to be measured changes sequentially through the slit 2a, and the shape and diameter of the light beam in the X direction are measured. Next f, g, h
i means that the beam shape and diameter in the Y direction of the light beam 1 to be measured are measured by the slit 2b.

Therefore, the light beam 1 to be measured is scanned from two orthogonal directions in the same cross section.

The same applies to the case of changing from i to a, and it is possible to scan in the Y direction and then scan in the X direction.

As described above, according to this embodiment, by providing two slits 2a and 2b orthogonal to each other in the same plane orthogonal to the optical axis of the light beam 1, two slits in the X and Y directions are provided on the same cross section. The shape and diameter of the light beam 1 in the direction can be measured simultaneously.

The present invention can be configured in various ways other than those shown in the above embodiments. For example, the angle that the two slits make with each other in the longitudinal direction and the direction of movement of the two slits are not limited to those shown in the above embodiments, but can be set as appropriate as necessary.

Effects of the Invention As described above, according to the present invention, the shape and diameter of the light beam in two directions can be set simultaneously on the same cross section.

[Brief explanation of drawings]

FIG. 1 shows the diameter of a light beam in one embodiment of the present invention. 1... Light beam to be measured, 2a, 2b...
・Slit, 3...Photodetector, 4...
Mobile device.

Claims (1)

[Claims] two slits that are not parallel to each other in the same plane perpendicular to the optical axis of the light beam, a moving device that moves these two slits in the plane perpendicular to the optical axis of the light beam, and a light beam transmitted from the slits. A light beam diameter measuring device comprising: a photodetector for detecting the amount of transmitted light.